Problems with A/C that the tech can not fix


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Old 06-14-16, 03:00 PM
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Problems with A/C that the tech can not fix

I have this problem with my aircon. i have had a tech over3 times and he has no idea what is going on. It has never happened when he has been there. It seems to happens more in the evening, but the tech wants a pretty hefty houry rate after hours, so i am looking for some help/ideas

Here is some info

1) the house is 3 years old
2) it is a gas furnace inside and aircon outside
3) i have two zones in the house
4) the tech has replaced a relay outside
5) i have replaced both thermostats with two new honeywell RTH9580WF

The problem is (really noticeable in the evening cause the lights flash alot - everytime it stops and starts)

The outside aircon will be running. When it appears to try to turn off, it turns on and off multiple times
To better explain the problem i have uploaded a video My Video . The problem happens at the 3:00 minute mark (sorry no editing tools)

Any suggestions would be greatly appreciated
Thanks
Randy
 
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Old 06-14-16, 03:24 PM
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I have seen this happen during brown out conditions. Though I only could hear in video.

Do you have an electric meter?

Can you test incoming voltage to the house? If voltage incoming is too low, sometimes the transformer will not have enough to supply 24v and may drop far enough to cause issues with relays/contactors/boards.

You could also have an electrical issue itself.

But just for sake of elimination, test incoming voltage to the house when no problems exist. Then retest if problem comes back.

Mainly I used to see this on rooftops that had transformers wired for 230v when they should have been 208v. At 208v, they would work, but on a hot day, the power company would only give us ~190v, which would either cause intermittent failure or roast the coils/transformer.
 

Last edited by JJinPA; 06-14-16 at 03:41 PM.
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Old 06-14-16, 03:42 PM
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thankyou for responding. So do you mean in my main electrical panel , check the incoming voltage to the house? I just want to verify that is what you are suggesting. thanks again for helping
 
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Old 06-14-16, 03:47 PM
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You can check at disconnect for the condenser or at the electrical panel. Just want to see what it adds up to...If less than 200v, that could be your issue...Evening tends to be when everyone gets home, cranks up AC, oven, TV's...etc. Sometimes only so much electric to go around. As the voltage drops, amperage goes up...Then eventually transformers go boom.

Obviously, be careful....

Edit: If you do find low voltage conditions, call power company and report.

Plus, as extra precaution, you may want to kill power to electronics/appliances as lower than expected voltage can cause damage to equipment.
 

Last edited by JJinPA; 06-14-16 at 04:09 PM.
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Old 06-17-16, 06:32 AM
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JJinPA, I went out side to where the outside unit has its own breaker.
i am having problems catching in a failed state but saw one anomaly and was wondering if this is an issue. It may not be your area of expertise , but thought i would ask.
On the breaker i am getting 240 ( it is constantly changing +/- 4 volts)
if i do one leg to ground i get a solid constant 121. If i do the other leg it is continuously +/- 3 volts. It is never is solid like the other leg. Is this something i need to be worried about or is this a red herring?
THanks again for your help
 
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Old 06-17-16, 08:29 AM
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Both sides of the 240VAC line referenced to ground should be rock solid and not varying +/- 3 volts. I would call your power company and tell them about it. This doesn't sound right to me.
 
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Old 06-17-16, 09:05 AM
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I agree.

Call power company and tell them you are experiencing possible brown out conditions. Ask if there are known issues in the area.

You may need to call an electrician to verify it is not a problem within the house.

Check the outlets your sensitive equipment is plugged into...TV, PC, etc. and make sure they are not fed by that leg that is not consistent.

You don't want those on a leg that is bouncing like that.

It is what I expected to find. Is is cooler now than when problem was occuring?

You can also check from R to C(low voltage) and see what you are getting(should be close to 24v). If that leg drops too far, your transformer won't appreciate it and could drop the 24v far enough to let go of contactor. Plus its not really good on the motors to run with "dirty" electric.

Your condenser tag says min operating voltage on it. I am unable to get pics at moment, but if it drops below that, it may have issues and should be shut off to safeguard the equipment.
 
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Old 06-17-16, 11:22 PM
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A few volts fluctuation on one leg is not uncommon.

Your problem doesn't sound like a voltage sag to me. If I had to guess.... you may be low on refrigerant. I guess we can assume your tech replaced the contactor which I'm quite sure he thought was bad due to the blackened contacts from banging open and closed like that.

My second guess would be you have a problem with your zone controlling module.
Do you know what it is ? It'll be near the furnace. A separate box with lots of wires.

You should buy an inexpensive voltmeter. A $15 special from the depot is all that's needed.

If you have the tech come back..... have him install a 5 minute time delay module.
 
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Old 06-20-16, 05:45 AM
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PJmax, Thanks for responding. Is the zone controlling module something i can replace on my own? As far as a 5 minute delay module, is that something that gets installed outside or down by the zone controlling module?
Btw, using the voltmeter what am i looking for ?
thanks
 
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Old 06-20-16, 09:54 AM
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You are using two wifi stats ?

Usually with a zoning system... one is the wifi and the other is a basic stat.
Do you know if you actually have a zone control panel ?
A make and model or picture of it would be helpful. http://www.doityourself.com/forum/el...-pictures.html
 
 

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